/*
 * Copyright 2008 ZXing authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/*namespace com.google.zxing.common.reedsolomon {*/

/*import java.util.ArrayList;*/
/*import java.util.List;*/

import GenericGF from './GenericGF'
import GenericGFPoly from './GenericGFPoly'
import Exception from './../../Exception'
import System from './../../util/System'

/**
 * <p>Implements Reed-Solomon encoding, as the name implies.</p>
 *
 * @author Sean Owen
 * @author William Rucklidge
 */
export default class ReedSolomonEncoder {

  private field: GenericGF
  private cachedGenerators: GenericGFPoly[]

  public constructor(field: GenericGF) {
    this.field = field
    this.cachedGenerators = []
    this.cachedGenerators.push(new GenericGFPoly(field, Int32Array.from([1])));
  }

  private buildGenerator(degree: number /*int*/): GenericGFPoly {
    const cachedGenerators = this.cachedGenerators
    if (degree >= cachedGenerators.length) {
      let lastGenerator = cachedGenerators[cachedGenerators.length - 1]
      const field = this.field
      for (let d = cachedGenerators.length; d <= degree; d++) {
        const nextGenerator = lastGenerator.multiply(
            new GenericGFPoly(field, Int32Array.from([1, field.exp(d - 1 + field.getGeneratorBase()) ])));
        cachedGenerators.push(nextGenerator)
        lastGenerator = nextGenerator
      }
    }
    return cachedGenerators[degree]
  }

  public encode(toEncode: Int32Array, ecBytes: number /*int*/): void {
    if (ecBytes === 0) {
      throw new Exception(Exception.IllegalArgumentException, "No error correction bytes")
    }
    const dataBytes = toEncode.length - ecBytes
    if (dataBytes <= 0) {
      throw new Exception(Exception.IllegalArgumentException, "No data bytes provided")
    }
    const generator = this.buildGenerator(ecBytes)
    const infoCoefficients: Int32Array = new Int32Array(dataBytes)
    System.arraycopy(toEncode, 0, infoCoefficients, 0, dataBytes)
    let  info = new GenericGFPoly(this.field, infoCoefficients)
    info = info.multiplyByMonomial(ecBytes, 1)
    const remainder = info.divide(generator)[1]
    const coefficients = remainder.getCoefficients()
    const numZeroCoefficients = ecBytes - coefficients.length
    for (let i = 0; i < numZeroCoefficients; i++) {
      toEncode[dataBytes + i] = 0
    }
    System.arraycopy(coefficients, 0, toEncode, dataBytes + numZeroCoefficients, coefficients.length)
  }

}
